Light functioning through at least two photoreceptors controls chloroplast development in Euglena by regulating nuclear and chloroplast genome transcription. Ethanol inhibits light-induced chlorophyll synthesis and the synthesis of at least one light-induced chloroplast localized enzyme NADP glyceraldehyde-3-phosphate dehydrogenase. Ethanol induced glyoxysome formation in Euglena while light appears to inhibit this process. To better understand the factors regulating organelle development in Euglena, the individual and simultaneous effect of light and ethanol on the activity of enzymes localized in specific organelles will be studied. The enzymes to be studied are: cytoplasmic valyl-tRNA synthetase, chloroplast valyl-tRNA synthetase, phosphoglycollate phosphatase, hydroxypyruvate reductase, fumarase, serine hydroxymethyltransferase, and malate synthetase. These enzymes are localized in the cytoplasm, chloroplast, peroxisome, and mitochondria. Studies will also be performed using the plastidless mutants W3BUL and Wl0SmL in order to elucidate the role the cytoplasmic photoreceptor plays in the regulation of organelle biogenesis.